The present invention relates generally to footplates having a range of adjustment, and more specifically, to a quick release footplate assembly for a jigsaw.
Jigsaws are used to cut fine patterns in a workpiece such as lines, circles, curves, and the like. The relatively thin blade of the jigsaw, as opposed, for example, to the relatively large blade of a circular saw, make it ideal for cutting operations which still need to be precise but are not necessarily in a straight line. Portable jigsaws typically include a housing containing an electric motor for reciprocating a saw blade which extends perpendicularly from the bottom of the housing and having cutting teeth that face toward the front of the housing. Typically, a footplate is disposed at the bottom of the housing and provides a generally flat surface to support and guide the jigsaw during cutting. The flat bottom of the footplate is placed on, and slides over, a workpiece being cut so that the operator can guide the blade to obtain the desired cut. The footplate has a slot through which the saw blade extends to engage the workpiece and during cutting the blade reciprocates at this position while the jigsaw is moved in a generally forward direction.
Some jigsaws can also be used to form bevel-edge cuts, which are cuts formed at an angle with respect to the plane of the bottom of the footplate. Such jigsaws include a mechanism for adjusting and locking the position of the footplate with respect to the housing and the saw blade. In use, the blade maintains its perpendicular orientation with respect to the housing, but is at a different angular orientation with respect to the plane of the bottom of the footplate. Thus, since the planar surface of the footplate remains in contact with the planar surface of the workpiece, when the saw blade is maintained at an angle with respect to the footplate, the resulting cutting operation will also be at an angle.
The prior art discloses various mechanisms for adjusting and locking the position of the footplate with respect to the blade of a jigsaw. One such arrangement is disclosed, for example, in U.S. Pat. No. 5,727,322 to Giacometti, assigned to Black and Decker, Inc. As illustrated in FIG. 2 of Giacometti, the locking and adjustment mechanism requires a relatively complex arrangement of many different components. The locking mechanism 58 includes first 114, second 134 and third 152 plates. A locking portion 170 of a lever 60 is disposed between the second 134 and third 152 plates. As shown in FIG. 7, the locking portion 170 of the lever 60 has a wide cross section 180, which is used to force the clamping plates apart and lock the footplate, and a narrow cross section 182, which is used to allow the clamping plates to relax and adjust the footplate. Such an arrangement, however, suffers from many disadvantages. First, the locking portion 170 of the lever 60 provides a movement which is difficult and jerky. Second, as seen in FIG. 10, adjustment of the footplate requires moving the lever 60 beyond the footplate 62, a movement that requires the entire jigsaw to be turned upside-down and does not allow adjustment while the footplate and jigsaw rest upon a workpiece. Third, as seen from FIG. 11, when adjusting the bevel to its extreme angular position, the extent of the angle is limited by the lever and the movement of the lever interferes with the footplate.
Other disadvantages are apparent as well and are similarly present with other prior art designs.
It is therefore an object of the present invention to provide an improved footplate assembly with a locking and releasing mechanism that allows for easier adjustment thereof.
It is another object of the present invention to provide a footplate assembly that has a simpler design and without a great number of additional components as found in the prior art.
It is also an object of the present invention to provide a footplate assembly that allows for convenient beveled adjustment of the footplate without requiring turning the jigsaw upside-down.
It is a further object of the present invention to provide a footplate assembly that allows for beveled adjustment through a mechanism that provides a smooth transition of force from a released to a locked position so as not to risk misalignment of the desired bevel setting.
It is a further object of the present invention to provide a footplate assembly that does not interfere with the footplate when adjusted to its extreme beveled position. As such, it would be beneficial that the jigsaw need not be turned entirely around in order to access such locking means and that it not interfere with the footplate itself.
The above objects are realized in the present invention which provides a jigsaw footplate adjustment mechanism that produces smooth and even translation of rotational movement to vertical movement. The mechanism includes a cam arrangement with a handle disposed at the back of the jigsaw to provide a smooth camming movement that does not interfere with the position of the footplate.
According to one embodiment of the present invention, there is provided a releasable footplate assembly for a jigsaw including a shaft portion having a handle, a screw boss that rotationally receives a cam portion of the shaft, a base portion having a bridge through which a screw extends, and a bridge plate attached to the screw, which serves to selectively engage the bridge portion of the footplate.
According to a second embodiment of the present invention, there is provided a releasable footplate assembly for a jigsaw including a shaft portion having a handle, a retaining bolt that rotationally receives a cam portion of the shaft, a base portion having a bridge through which the retaining bolt extends, and a bridge plate attached to the retaining bolt with a nut, which serves to selectively engage the bridge portion of the footplate.